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Articoli di riviste sul tema "LuxR"

1

Bazhenov, Sergey, Olga Melkina, Vadim Fomin, Ekaterina Scheglova, Pavel Krasnik, Svetlana Khrulnova, Gennadii Zavilgelsky e Ilya Manukhov. "LitR directly upregulates autoinducer synthesis and luminescence in Aliivibrio logei". PeerJ 9 (21 settembre 2021): e12030. http://dx.doi.org/10.7717/peerj.12030.

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Abstract (sommario):
LitR is a master-regulator of transcription in the ainS/R and luxS/PQ quorum sensing (QS) systems of bacteria from Vibrio and Aliivibrio genera. Here, we for the first time directly investigated the influence of LitR on gene expression in the luxI/R QS system of psychrophilic bacteria Aliivibrio logei. Investigated promoters were fused with Photorhabdus luminescens luxCDABE reporter genes cassette in a heterological system of Escherichia coli cells, litR A. logei was introduced into the cells under control of Plac promoter. LitR has been shown to upregulate genes of autoinducer synthase (luxI), luciferase and reductase (luxCDABE), and this effect doesn’t depend on presence of luxR gene. To a much lesser degree, LitR induces luxR1, but not the luxR2 — the main luxI/R regulator. Enhanced litR expression leads to an increase in a LuxI-autoinducer synthesis and a subsequent LuxR-mediated activation of the luxI/R QS system. Effect of LitR on luxI transcription depends on lux-box sequence in luxI promoter even in absence of luxR (lux-box is binding site of LuxR). The last finding indicates a direct interaction of LitR with the promoter in the lux-box region. Investigation of the effect of LitR A. logei on luxI/R QS systems of mesophilic Aliivibrio fischeri and psychrophilic Aliivibrio salmonicida showed direct luxR-independent upregulation of luxI and luxCDABE genes. To a lesser degree, it induces luxR A. fischeri and luxR1 A. salmonicida. Therefore, we assume that the main role of LitR in cross-interaction of these three QS systems is stimulating the expression of luxI.
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2

Bazhenov, Sergey, Uliana Novoyatlova, Ekaterina Scheglova, Vadim Fomin, Svetlana Khrulnova, Olga Melkina, Vladimir Chistyakov e Ilya Manukhov. "Influence of the luxR Regulatory Gene Dosage and Expression Level on the Sensitivity of the Whole-Cell Biosensor to Acyl-Homoserine Lactone". Biosensors 11, n. 6 (23 maggio 2021): 166. http://dx.doi.org/10.3390/bios11060166.

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Abstract (sommario):
Aliivibrio fischeri LuxR and Aliivibrio logei LuxR1 and LuxR2 regulatory proteins are quorum sensing transcriptional (QS) activators, inducing promoters of luxICDABEG genes in the presence of an autoinducer (3-oxo-hexanoyl-l-homoserine lactone). In the Aliivibrio cells, luxR genes are regulated by HNS, CRP, LitR, etc. Here we investigated the role of the luxR expression level in LuxI/R QS system functionality and improved the whole-cell biosensor for autoinducer detection. Escherichia coli-based bacterial lux-biosensors were used, in which Photorhabdus luminescensluxCDABE genes were controlled by LuxR-dependent promoters and luxR, luxR1, or luxR2 regulatory genes. We varied either the dosage of the regulatory gene in the cells using additional plasmids, or the level of the regulatory gene expression using the lactose operon promoter. It was shown that an increase in expression level, as well as dosage of the regulatory gene in biosensor cells, leads to an increase in sensitivity (the threshold concentration of AI is reduced by one order of magnitude) and to a two to threefold reduction in response time. The best parameters were obtained for a biosensor with an increased dosage of luxRA. fischeri (sensitivity to 3-oxo-hexanoyl-l-homoserine lactone reached 30–100 pM).
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3

Urbanowski, M. L., C. P. Lostroh e E. P. Greenberg. "Reversible Acyl-Homoserine Lactone Binding to Purified Vibrio fischeri LuxR Protein". Journal of Bacteriology 186, n. 3 (1 febbraio 2004): 631–37. http://dx.doi.org/10.1128/jb.186.3.631-637.2004.

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Abstract (sommario):
ABSTRACT The Vibrio fischeri LuxR protein is the founding member of a family of acyl-homoserine lactone-responsive quorum-sensing transcription factors. Previous genetic evidence indicates that in the presence of its quorum-sensing signal, N-(3-oxohexanoyl) homoserine lactone (3OC6-HSL), LuxR binds to lux box DNA within the promoter region of the luxI gene and activates transcription of the luxICDABEG luminescence operon. We have purified LuxR from recombinant Escherichia coli. Purified LuxR binds specifically and with high affinity to DNA containing a lux box. This binding requires addition of 3OC6-HSL to the assay reactions, presumably forming a LuxR-3OC6-HSL complex. When bound to the lux box at the luxI promoter in vitro, LuxR-3OC6-HSL enables E. coli RNA polymerase to initiate transcription from the luxI promoter. Unlike the well-characterized LuxR homolog TraR in complex with its signal (3-oxo-octanoyl-HSL), the LuxR-30C6-HSL complex can be reversibly inactivated by dilution, suggesting that 3OC6-HSL in the complex is not tightly bound and is in equilibrium with the bulk solvent. Thus, although LuxR and TraR both bind 3-oxoacyl-HSLs, the binding is qualitatively different. The differences have implications for the ways in which these proteins respond to decreases in signal concentrations or rapid drops in population density.
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4

Antunes, Luis Caetano M., Rosana B. R. Ferreira, C. Phoebe Lostroh e E. Peter Greenberg. "A Mutational Analysis Defines Vibrio fischeri LuxR Binding Sites". Journal of Bacteriology 190, n. 13 (14 dicembre 2007): 4392–97. http://dx.doi.org/10.1128/jb.01443-07.

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Abstract (sommario):
ABSTRACT Vibrio fischeri quorum sensing involves the LuxI and LuxR proteins. The LuxI protein generates the quorum-sensing signal N-3-oxohexanoyl-l-homoserine lactone (3OC6-HSL), and LuxR is a signal-responsive transcriptional regulator which activates the luminescence (lux) genes and 17 other V. fischeri genes. For activation of the lux genes, LuxR binds to a 20-base-pair inverted repeat, the lux box, which is centered 42.5 base pairs upstream of the transcriptional start of the lux operon. Similar lux box-like elements have been identified in only a few of the LuxR-activated V. fischeri promoters. To better understand the DNA sequence elements required for LuxR binding and to identify binding sites in LuxR-regulated promoters other than the lux operon promoter, we have systematically mutagenized the lux box and evaluated the activity of many mutants. By doing so, we have identified nucleotides that are critical for promoter activity. Interestingly, certain lux box mutations allow a 3OC6-HSL-independent LuxR activation of the lux operon promoter. We have used the results of the mutational analysis to create a consensus lux box, and we have used this consensus sequence to identify LuxR binding sites in 3OC6-HSL-activated genes for which lux boxes could not be identified previously.
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5

Swearingen, Matthew C., Anice Sabag-Daigle e Brian M. M. Ahmer. "Are There Acyl-Homoserine Lactones within Mammalian Intestines?" Journal of Bacteriology 195, n. 2 (9 novembre 2012): 173–79. http://dx.doi.org/10.1128/jb.01341-12.

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Abstract (sommario):
ABSTRACTManyProteobacteriaare capable of quorum sensing usingN-acyl-homoserine lactone (acyl-HSL) signaling molecules that are synthesized by LuxI or LuxM homologs and detected by transcription factors of the LuxR family. Most quorum-sensing species have at least one LuxR and one LuxI homolog. However, members of theEscherichia,Salmonella,Klebsiella, andEnterobactergenera possess only a single LuxR homolog, SdiA, and no acyl-HSL synthase. The most obvious hypothesis is that these organisms are eavesdropping on acyl-HSL production within the complex microbial communities of the mammalian intestinal tract. However, there is currently no evidence of acyl-HSLs being produced within normal intestinal communities. A few intestinal pathogens, includingYersinia enterocolitica, do produce acyl-HSLs, andSalmonellacan detect them during infection. Therefore, a more refined hypothesis is that SdiA orthologs are used for eavesdropping on other quorum-sensing pathogens in the host. However, the lack of acyl-HSL signaling among the normal intestinal residents is a surprising finding given the complexity of intestinal communities. In this review, we examine the evidence for and against the possibility of acyl-HSL signaling molecules in the mammalian intestine and discuss the possibility that related signaling molecules might be present and awaiting discovery.
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6

Antunes, Luis Caetano M., Amy L. Schaefer, Rosana B. R. Ferreira, Nan Qin, Ann M. Stevens, Edward G. Ruby e E. Peter Greenberg. "Transcriptome Analysis of the Vibrio fischeri LuxR-LuxI Regulon". Journal of Bacteriology 189, n. 22 (7 settembre 2007): 8387–91. http://dx.doi.org/10.1128/jb.00736-07.

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Abstract (sommario):
ABSTRACT The Vibrio fischeri quorum-sensing signal N-3-oxohexanoyl-l-homoserine lactone (3OC6-HSL) activates expression of the seven-gene luminescence operon. We used microarrays to unveil 18 additional 3OC6-HSL-controlled genes, 3 of which had been identified by other means previously. We show most of these genes are regulated by the 3OC6-HSL-responsive transcriptional regulator LuxR directly. This demonstrates that V. fischeri quorum sensing regulates a substantial number of genes other than those involved in light production.
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7

von Bodman, Susanne B., Jessica K. Ball, Marie A. Faini, Carmen M. Herrera, Timothy D. Minogue, Mark L. Urbanowski e Ann M. Stevens. "The Quorum Sensing Negative Regulators EsaR and ExpREcc, Homologues within the LuxR Family, Retain the Ability To Function as Activators of Transcription". Journal of Bacteriology 185, n. 23 (1 dicembre 2003): 7001–7. http://dx.doi.org/10.1128/jb.185.23.7001-7007.2003.

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Abstract (sommario):
ABSTRACT Most LuxR homologues function as activators of transcription during the process of quorum sensing, but a few, including EsaR and ExpR Ecc , negatively impact gene expression. The LuxR-activated luxI promoter and LuxR binding site, the lux box, were used in artificial contexts to assess the potential for transcriptional activation and DNA binding by EsaR and ExpR Ecc . Although the acyl-homoserine lactone responsiveness of both proteins is the opposite of that shown by most LuxR family members, EsaR and ExpR Ecc have preserved the ability to interact with RNA polymerase and activate transcription despite their low affinity for the lux box DNA.
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8

Subramoni, Sujatha, e Vittorio Venturi. "LuxR-family ‘solos’: bachelor sensors/regulators of signalling molecules". Microbiology 155, n. 5 (1 maggio 2009): 1377–85. http://dx.doi.org/10.1099/mic.0.026849-0.

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Abstract (sommario):
N-Acylhomoserine lactone (AHL) quorum-sensing (QS) signalling is the best-understood chemical language in proteobacteria. In the last 15 years a large amount of research in several bacterial species has revealed in detail the genetic, molecular and biochemical mechanisms underlying AHL signalling. These studies have revealed the role played by protein pairs of the AHL synthase belonging to the LuxI family and cognate LuxR-family AHL sensor–regulator. Proteobacteria however commonly possess a QS LuxR-family protein for which there is no obvious cognate LuxI synthase; these proteins are found in bacteria which possess a complete AHL QS system(s) as well as in bacteria that do not. Scientists are beginning to address the roles played by these proteins and it is emerging that they could allow bacteria to respond to endogenous and exogenous signals produced by their neighbours. AHL QS research thus far has mainly focused on a cell-density response involving laboratory monoculture studies. Recent findings on the role played by the unpaired LuxR-family proteins highlight the need to address bacterial behaviour and response to signals in mixed communities. Here we review recent progress with respect to these LuxR proteins, which we propose to call LuxR ‘solos’ since they act on their own without the need for a cognate signal generator. Initial investigations have revealed that LuxR solos have diverse roles in bacterial interspecies and interkingdom communication.
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9

McDougald, Diane, Scott A. Rice e Staffan Kjelleberg. "SmcR-Dependent Regulation of Adaptive Phenotypes inVibrio vulnificus". Journal of Bacteriology 183, n. 2 (15 gennaio 2001): 758–62. http://dx.doi.org/10.1128/jb.183.2.758-762.2001.

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ABSTRACT Vibrio vulnificus contains homologues of the V. harveyi luxR and luxS genes. A null mutation insmcR (luxR) resulted in a defect in starvation survival, inhibition of starvation-induced maintenance of culturability that occurs when V. vulnificusis starved prior to low-temperature incubation, and increased expression of stationary-phase phenotypes.
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10

Gray, Kendall M., e James R. Garey. "The evolution of bacterial LuxI and LuxR quorum sensing regulators". Microbiology 147, n. 8 (1 agosto 2001): 2379–87. http://dx.doi.org/10.1099/00221287-147-8-2379.

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Tesi sul tema "LuxR"

1

Faini, Marie Annette. "Transcriptional Control during Quorum Sensing by LuxR and LuxR Homologues". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31994.

Testo completo
Abstract (sommario):
Quorum sensing is a mechanism used by many proteobacteria to regulate expression of target genes in a population-dependent manner. The quorum sensing system of Vibrio fischeri activates the luminescence (lux) operon when the autoinducer signaling molecule (N-3-oxohexanoyl homoserine lactone) is recognized and bound by the activator protein LuxR. LuxR subsequently binds to the lux box centered at à 42.5 bp upstream of the transcription initiation site and activates transcription from the lux operon promoter, resulting in the emission of light at high cell densities. LuxR consists of 250 amino acids arranged into an N-terminal (regulatory) domain and a C-terminal (activation) domain, and is thought to function as an ambidextrous activator capable of making multiple contacts with the alpha and sigma subunits of RNA polymerase (RNAP). Published work describing the results of alanine scanning mutagenesis performed on the C-terminal domain of LuxR (residues 190-250) has identified residues (K198, W201 and I206) that appear to play a role in positive control of transcription initiation. Additional mutagenesis of residues 180-189 has been undertaken via a three-primer or four-primer PCR-based method in this study. Variants of LuxR were screened for their ability to activate luciferase production and to repress transcription from an artificial promoter, and production of full-length LuxR was measured, in an attempt to identify additional positive control variants. No additional positive control variants were found in this study. Work has also been undertaken to identify intergenic suppressors between positive control variants of LuxR and the RNAP alpha subunit, RpoA. Starting with a recombinant Escherichia coli strain encoding the lux operon and LuxR variant I206E, a random chemical mutagenesis was performed on a vector encoding RpoA. Following transformation of the mutated plasmids encoding RpoA, high throughput luminescence assays were used to identify isolates with phenotypes brighter than the control. Isolation of an intergenic suppressor will confirm the existence of protein-protein interactions between LuxR and RpoA within the transcription initiation complex. The ability of other LuxR family members to establish productive protein-protein interactions with RNAP necessary for transcription initiation was also examined. LuxR homologues EsaR of Pantoea stewarti ssp. stewartii, a repressor of known function, and ExpR of Erwinia carotovora subsp. carotovora were also analyzed for their ability to activate the lux operon, as well as to repress transcription from an artificial promoter containing the lux box.
Master of Science
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2

Collins, Cynthia Hollie Parker Carl Stevens. "Directed evolution of the transcriptional activator LuxR /". Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-12272005-160649.

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3

Brameyer, Sophie. "Cell-cell communication via LuxR solos in Photorhabdus species". Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-181139.

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Abstract (sommario):
Bacteria constantly need to monitor their environment and adapt the bacterial group-coordinated behaviour to changing habitats like nutrition alterations or host variations. Commonly cell-cell communication via acyl homoserine lactones (AHLs)is used to synchronise the behaviour of a bacterial population dependent on cell size. This process is referred to as quorum sensing (QS) and predominantly occurs in Gram-negative bacteria. The typical QS system consists of a LuxI-synthase that synthesises AHLs, and a LuxR-type receptor, which then responds to these AHLs. Upon AHL-binding, the LuxR-type receptor regulates the expression of different target genes and thus influences several processes, like biofilm formation, virulence, antibiotic production or cell-cell interaction. Interestingly, many proteobacteria possess additional LuxR homologs, but lack a cognate LuxI-type synthase. Those LuxR-type receptors are referred to as LuxR orphans or LuxR solos and can expand the regulatory QS network. Photorhabdus species are insect pathogenic bacteria, living in symbiosis with entomopathogenic nematodes. They all possess an exceptionally high number of LuxR solos, but lack LuxI homologs and therefore do not produce AHLs. The function of these LuxR solos, their role in cell-cell communication and the identification of their cognate signalling molecules in Photorhabdus species is the main focus of this work. In this thesis a novel signalling molecule used for QS could be identified for the first time in P. luminescens. This novel QS molecule is an α-pyrone named photopyrone (PPY) and produced endogenously by the photopyrone synthase (PpyS). The PPYs are specifically recognized by the LuxR solo regulator PluR, which then activates expression of the pcf (Photorhabdus clumping factor) operon leading to cell clumping of P. luminescens cells. Moreover, the PpyS/PluR quorum sensing system and its induced cell clumping contribute to the overall toxicity of P. luminescens. Furthermore, a second novel signalling molecule sensed by a LuxR solo of Photorhabdus species could be identified besides PPYs. The insect and human pathogenic bacteria P. asymbiotica lacks a PpyS homolog as well as a LuxI homolog, but harbours a pcf operon and a homologue to PluR, which is named PauR. The signalling molecule sensed by the LuxR-type receptor PauR could be identified, which is neither an AHL nor a PPY. PauR recognises a 2,5-dialkylresorcinol (DAR) produced by the DarABC pathway. Upon binding of the cognate signalling molecule, Summary XII PauR activates expression of the pcf operon. This also leads to cell clumping in P. asymbiotica. Furthermore, the DarABC/PauR QS system also contributes to the overall pathogenicity of P. asymbiotica against Galleria mellonella insect larvae. A bioinformatics approach revealed a high number of LuxR solos present in P. temperata and P. asymbiotica like in P. luminescens. Thereby, several conserved motives of amino acids could be identified, which are potentially important for signalbinding and -specificity. Variations in these amino acid motifs are assumed to reflect the overall variety of signals that can be sensed by LuxR solos. Furthermore, the specificity of the two LuxR solos PluR and PauR towards their cognate signalling molecules, PPYs and DARs, respectively, was analysed. Thereby, it could be shown that the previously identified conserved amino acid motives in the signal-binding domain (SBD), the TYDQCS-motif of PluR and the TYDQYI-motif of PauR, are essential but not sufficient for ligand-binding. Similar as for AHLs, it was unclear how the signalling molecules PPYs and DARs can cross the bacterial cell membrane. In the last part of this thesis the import mechanism for the Photorhabdus-specific signalling compounds PPYs and DARs were identified. Initial evidence could be provided that the membrane-integrated transporter FadL is mainly involved in the import of these hydrophobic compounds, and that they are not transported via simple diffusion across the cell membrane, which is assumed for AHLs. In conclusion, the data that is compiled presents two LuxR solos of Photorhabdus species adapted to sense and respond to novel non-AHL signalling molecules used for QS. Therefore, this thesis reveals that cell-cell communication via LuxR-type receptors goes far beyond AHL-signalling in nature.
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Trott, Amy Elizabeth. "Amino Acid Residues in LuxR Critical for its Mechanism of Transcriptional Activation during Quorum Sensing". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34070.

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Abstract (sommario):
Vibrio fischeri, a symbiotic bioluminescent bacterium, serves as one of the best understood model systems for a mechanism of cell-density dependent bacterial gene regulation known as quorum sensing. During quorum sensing in V. fischeri, an acylated homoserine chemical signal (autoinducer) is synthesized by the bacteria and used to sense their own species in a given environment. As the autoinducer levels rise, complexes form between the autoinducer and the N-terminal domain of a regulatory protein, LuxR. In response to autoinducer binding, LuxR is believed to undergo a conformational change that allows the C-terminal domain to activate transcription of the luminescence or lux operon. To further understand the mechanism of LuxR-dependent transcriptional activation of the lux operon, PCR-based site-directed mutagenesis procedures have been used to generate alanine-substitution mutants in the C-terminal forty-one amino acid residues of LuxR, a region that has been hypothesized to play a critical role in the activation process. An in vivo luminescence assay was first used to test the effects of the mutations on LuxR-dependent activation of the lux operon in recombinant Escherichia coli. Luciferase levels present in cell extracts obtained from these strains were also quantified and found to correlate with the luminescence results. Eight strains encoding altered forms of LuxR exhibited a "dark" phenotype with luminescence output less than 50% and luciferase levels less than 50% of the wildtype control strain. Western immunoblotting analysis with cell extracts from the luminescence and luciferase assays verified that the altered forms of LuxR were expressed at levels approximately equal to wildtype. Therefor, Low luminescence and luciferase levels could be the result of a mutation that either affects the ability of LuxR to recognize and bind its DNA target (the lux box) or to establish associations with RNA polymerase (RNAP) at the lux operon promoter necessary for transcriptional initiation. A third in vivo assay was used to test the ability of the altered forms of LuxR to bind to the lux box (DNA binding assay/repression). All of the LuxR variants exhibiting the "dark" phenotype in the luminescence and luciferase assay were also found to be unable to bind to the lux box in the DNA binding assay. Therefore, it can be concluded that the alanine substitutions made at these positions affect the ability of LuxR to bind to the lux box in the presence and absence of RNA polymerase. Another class of mutants exhibited wildtype phenotypes in the luminescence and luciferase assays but were unable to bind to the lux box in the DNA binding assay. The alanine substitutions made at these amino acid residues may be making contacts with RNAP that are important for maintaining the stability of the DNA binding region of LuxR. Alanine substitutions made at these positions have a defect in DNA binding at the promoter of the lux operon only in the absence of RNAP. None of the alanine substitutions made in the C-terminal forty-one amino acids of LuxR were found to affect activation of transcription of the lux operon without also affecting DNA binding. Taken together, these results support the conclusion that the C-terminal forty-one amino acids of LuxR are important for DNA recognition and binding of the lux box rather than positive control of the process of transcription initiation.
Master of Science
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5

Poulter, Simon. "The LuxR-family quorum sensing transcriptional regulator CarR in Erwinia and Serratia". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609398.

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6

Brameyer, Sophie [Verfasser], e Ralf [Akademischer Betreuer] Heermann. "Cell-cell communication via LuxR solos in Photorhabdus species / Sophie Brameyer. Betreuer: Ralf Heermann". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1069491438/34.

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7

Qin, Nan. "Analysis of the Regulons Controlled by Transcriptional Regulators LuxR and LitR in Vibrio fischeri". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28433.

Testo completo
Abstract (sommario):
Quorum sensing is a bacterial signaling system that controls gene expression in a population density-dependent manner. In Gram-negative proteobacteria, the cell density control of luminescence was first observed in the symbiotic marine bacterium Vibrio fischeri and this system is one of the best studied quorum sensing systems. Two-dimensional sodium dodecyl sulfate-polyacrylamide (2D-SDS) gel electrophoresis analysis previously identified several non-Lux proteins in V. fischeri MJ-100 whose expression was dependent on LuxR and 3-oxo-hexanoyl-L-homoserine lactone (3-oxo-C6-HSL). A lacZ reporter was used to show that the promoters for qsrP, acfA, and ribB were directly activated via LuxR-3-oxo-C6-HSL in recombinant Escherichia coli. The sites of transcription initiation were established via primer extension analysis. Based on the position of the lux box-binding site near position â 40, all three promoters appear to have a class II-type promoter structure. Real-time reverse transcription-PCR was used to study the temporal expression of qsrP, acfA, and ribB during the exponential and stationary phases of growth, and electrophoretic mobility shift assays were used to compare the binding affinities of LuxR to the promoters under investigation. In order to fully characterize the LuxR regulon in V. fischeri ES114, microarray analysis was performed in the Greenberg lab (University of Washington) and 18 LuxR-3-oxo-C6-HSL regulated promoters were found including 2 genes (qsrP and acfA) identified previously in MJ-100 in addition to the well-studied lux operon. In collaboration with them, full-length purified LuxR protein was used to show direct interaction between the LuxR protein and 7 genes/operons newly identified out of 13 genes/operons examined. The binding affinity between LuxR proteins and those genes was also measured. Based on the sequence of the lux boxes of the known genes regulated by LuxR and LitR, a position specific weight matrix (PSWM) was created and used to search through the intergenic regions of the V. fischeri ES114 genome. Some potential LuxR and LitR-regulated genes with high score were tested experimently to confirm direct activation. For the LuxR regulon, these possible LuxR-regulated promoters were cloned into a lacZ reporter and tested for their LuxR dependence. Beyond the genes found in microarray, the promoter of the intergenic region VFA0658-0659 was found to be activated by LuxR and 3-oxo-C6-HSL. For the LitR regulon, two LitR-regulated genes found in the microarray were also identified using PSWM and confirmed by real-time PCR to be dependent on LitR for expression. EMSA experiments showed that LitR can specifically bind to the litR boxes of LitR-regulated genes, litR and VF0170 which confirmed that the regulation is direct.
Ph. D.
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8

Williams, Joshua W. "Multi-tiered Regulation of luxR Provides Precise Timing and Maintenance of the Quorum Sensing Response of Vibrio fischeri". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/38580.

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The quorum-sensing response of Vibrio fischeri involves a complex network of genes (encoding regulatory proteins as well as sRNAs), that govern host-association and production of bioluminescence. A key regulator of this system is LuxR, which is the transcriptional activator of the lux operon as well as several other genes in. LuxR also autoregulates its own transcription, which we have shown causes bistability and hysteresis in the quorum-sensing response. This behavior allows the system to maintain a stable and robust response in the face of environmental fluctuation or decreases in external autoinducer concentration caused by other sources. There are many factors that are known to regulate luxR expression, including the ArcA redox-responsive regulator, the cAMP-CRP secondary metabolism regulator, and components of the quorum-sensing pathway like LitR. Because of this, LuxR levels are critical in both the timing of quorum-sensing induction, as well as the maintenance of the response over time. This makes it a potential target for multiple levels of regulation in response to factors such as environmental and metabolic conditions, as well as other components of the quorum-sensing network. Another important global regulatory protein in V. fischeri (and most other species of Gram-negative proteobacteria) is the post-transcriptional regulator CsrA. CsrA controls processes involved in carbon storage and utilization, as well as the transition from exponential to stationary phase growth. We have demonstrated that CsrA is regulated by two sRNAs (CsrB1 and CsrB2) in V. fischeri. Because CsrA regulates changes in cell behavior and is an important metabolic regulator, there is a good possibility that it has some interactions with the quorum-sensing regulon, whose endproduct, bioluminescence, creates a large metabolic demand from the cell. In an effort to determine at which point in the quorum-sensing regulatory network CsrA regulation is important, epistasis experiments were designed using factorial design, which is a subset of statistical analysis of variance (ANOVA). This method was used to generate a high degree of confidence in the data, so that even minor interactions in the regulatory networks could be established. By altering the levels of CsrA expression in various mutant strains of V. fischeri, we have demonstrated that CsrA acts by an unknown mechanism to increase the transcription of luxR when the quorum-sensing regulator LitR is absent. Our results also demonstrated that CsrA mediates this effect through repression of ArcA activity, which is known to act directly on the luxR and luxI intergenic region as a repressor. This indicates that CsrA may bypass the upstream parts of the quorum-sensing regulatory cascade that lead to litR activation, so that LitR and LuxR may be regulated differently in response to certain conditions. This work has shown that the interactions between global regulons can coordinately control the amount of quorum-sensing induction by affecting the level of LuxR in the cell. The balance of these regulatory networks allows the cell to tightly regulate the quorum-sensing response. Thus, LuxR serves as a critical regulatory hub in the cell, at which multiple signals can be integrated in order to generate the appropriate cellular response.
Ph. D.
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Callahan, Sean M. (Sean Michael) 1966. "The quorum-sensing regulation of Vibrio fischeri : novel components of the autoinduce/LuxR regulatory circuit". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85290.

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Dyszel, Jessica L. "Phenotypes of the LuxR Homolog, SdiA, in Salmonella and E. coli". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243943752.

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Libri sul tema "LuxR"

1

Callahan, Sean M. The quorum-sensing regulon of Vibrio fischeri: Novel components of the autoinducer/LuxR regulatory circuit. Cambridge, Mass: Massachusetts Institute of Technology, 1999.

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Callahan, Sean M. The quorum-sensing regulon of Vibrio fischeri: Novel components of the autoinducer/LuxR regulatory circuit. Cambridge, Mass: Massachusetts Institute of Technology, 1999.

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3

Anwen, Herbert-Lewis. Luxe. New York, NY]: the Calhoun School, 2013.

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Blanckaert, Christian. Luxe. Paris: Cherche midi, 2007.

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The Luxe (Luxe Series, Book 1). New York: HarperTeen, 2007.

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Godbersen, Anna. The Luxe (Luxe Series, Book 1). London: Penguin Books, 2008.

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Cairo, Luxor. [Glasgow]: HarperCollins, 1991.

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Sortland, Bjørn. Luxor-mysteriet. Oslo: Aschehoug, 2001.

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Blanckaert, Christian. Luxe trotter. Paris: Cherche midi, 2012.

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Venturi, Vittorio, e Brian M. M. Ahmer, a cura di. LuxR Solos are Becoming Major Players in Cell-Cell Communication in Bacteria. Frontiers Media SA, 2016. http://dx.doi.org/10.3389/978-2-88919-917-4.

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Capitoli di libri sul tema "LuxR"

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Kumar, Manoj, e Akanksha Rajput. "Phylogenomics and Evolutionary Perspective of Quorum Sensing Regulators (LuxI/LuxR) in Prokaryotes". In Quorum Sensing and its Biotechnological Applications, 61–70. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0848-2_4.

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Brameyer, Sophie, e Ralf Heermann. "Quorum Sensing and LuxR Solos in Photorhabdus". In Current Topics in Microbiology and Immunology, 103–19. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/82_2016_28.

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Winans, Stephen C., Ching-Sung Tsai, Gina T. Ryan, Ana Lidia Flores-Mireles, Esther Costa, Kevin Y. Shih, Thomas C. Winans, Youngchang Kim, Robert Jedrzejczak e Gekleng Chhor. "LuxR-type Quorum-sensing Regulators That Are Antagonized by Cognate Pheromones". In Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria, 1221–31. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119004813.ch118.

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Schuster, Martin, e E. P. Greenberg. "LuxR-Type Proteins in Pseudomonas aeruginosa Quorum Sensing: Distinct Mechanisms with Global Implications". In Chemical Communication among Bacteria, 131–44. Washington, DC, USA: ASM Press, 2014. http://dx.doi.org/10.1128/9781555815578.ch9.

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Gooch, Jan W. "Lux". In Encyclopedic Dictionary of Polymers, 436. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_7081.

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Weik, Martin H. "lux". In Computer Science and Communications Dictionary, 947. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_10792.

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Okonkwo, Uche. "Le new luxe". In Luxury Fashion Branding, 225–45. London: Palgrave Macmillan UK, 2007. http://dx.doi.org/10.1007/978-0-230-59088-5_8.

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Ryutova-Kemoklidze, Margarita. "Fiat Lux". In The Quantum Generation, 19–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-49357-7_2.

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Newman, Jane D., e Julia C. van Kessel. "Purification of the Vibrio Quorum-Sensing Transcription Factors LuxR, HapR, and SmcR". In Methods in Molecular Biology. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/7651_2020_306.

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Perruchon, Véronique. "Entre luxe et lux : naissance du noir". In Noir. Lumière et théâtralité, 17–54. Presses universitaires du Septentrion, 2016. http://dx.doi.org/10.4000/books.septentrion.8900.

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Atti di convegni sul tema "LuxR"

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Crook, A. N., A. V. Domenican, N. E. Gogolev, Yu V. Gogolev e E. A. Nikolaychik. "Two transcription factors of the LuxR family determine the virulent properties of Pectobacterium spp. through transcriptional control of one gene of the global regulator". In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-239.

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Corona, Igino, Davide Maiorca, Davide Ariu e Giorgio Giacinto. "Lux0R". In the 2014 Workshop. New York, New York, USA: ACM Press, 2014. http://dx.doi.org/10.1145/2666652.2666657.

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Rasoulinezhad, Seyedramin, Siddhartha, Hao Zhou, Lingli Wang, David Boland e Philip H. W. Leong. "LUXOR". In FPGA '20: The 2020 ACM/SIGDA International Symposium on Field-Programmable Gate Arrays. New York, NY, USA: ACM, 2020. http://dx.doi.org/10.1145/3373087.3375303.

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Bezerra, Diogo Henrique Duarte, Denio Mariz Timóteo Sousa, Guido Lemos de Souza Filho, Aquiles Medeiros Filgueira Burlamaqui e Igor Rosberg Medeiros Silva. "Luar". In the 18th Brazilian symposium. New York, New York, USA: ACM Press, 2012. http://dx.doi.org/10.1145/2382636.2382718.

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Airil, Muhammad Syukri. "Isolation of Bioluminescence Bacterium from Marine Fish and Amplification of Luciferase (lux AB) Gene". In INTERNATIONAL CONFERENCE ON BIOLOGICAL RESEARCH AND APPLIED SCIENCE. Jinnah University for Women, Karachi,Pakistan, 2022. http://dx.doi.org/10.37962/ibras/2022/10-13.

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Bioluminescence bacteria (BLB) are the most abundant and widely distributed light-emitting organisms that can be found in the marine environment. They are suitable for detecting pollution or integrated into bioluminescent imaging due to their ability to luminesce. However, there are limited studies regarding bioluminescent bacteria in terms of distribution and species present in Malaysia. This study aims to isolate BLB and amplify the luciferase (luxAB) genes. Bioluminescent bacteria were isolated from the guts of marine fish, Selaroidesleptolepis and streak onto luminescence agar (LA). The brightest luminous colony present in the dark was marked and streaked again obtain a pure colony. Then, the pure culture of the colony was subjected to genomic extraction before luxAB genes amplification and phylogenetic analysis. As a result, BLB were successfully isolated and identified to be Photobacteriumleiognathis train SYA2 (MZ491870.1). Genes encoding for luciferase enzyme were also amplified and sequenced with the size of luxA and luxB were 767 bp and 943 bp, respectively. Pairwise distance showed that the isolate has the highest similarity to P. leiognathi (DQ790853) with 99.66% and the lowest similarity to P. kishitanii (AY642227) with 69.84%. The information about the isolate will contribute to the distribution of BLB in Malaysia as well as potential of BLB as a biosensor and bioreporter.
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"LUAR 2005 Workshop". In 2005 International Conference on Cyberworlds (CW'05). IEEE, 2005. http://dx.doi.org/10.1109/cw.2005.60.

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Blue, Logan, Samuel Marchal, Patrick Traynor e N. Asokan. "Lux". In IoTDI '21: International Conference on Internet-of-Things Design and Implementation. New York, NY, USA: ACM, 2021. http://dx.doi.org/10.1145/3450268.3453530.

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Paredes, Pablo, Ryuka Ko, Eduardo Calle-Ortiz, John Canny, Björn Hartmann e Greg Niemeyer. "Fiat-Lux". In DIS '16: Designing Interactive Systems Conference 2016. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2901790.2901832.

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Debevec, Paul, Tim Hawkins, Westley Sarokin, Haarm-Pieter Duiker, Tal Garfinkel, Christine Cheng e Jenny Huang. "Fiat lux". In ACM SIGGRAPH 99 Electronic art and animation catalog. New York, New York, USA: ACM Press, 1999. http://dx.doi.org/10.1145/312379.312925.

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Samuell, Gemma. "Lux "Neon Girl"". In ACM SIGGRAPH 2008 computer animation festival. New York, New York, USA: ACM Press, 2008. http://dx.doi.org/10.1145/1400468.1400516.

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Rapporti di organizzazioni sul tema "LuxR"

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Mount, B. J. LUX-ZEPLIN (LZ) Technical Design Report. Office of Scientific and Technical Information (OSTI), marzo 2017. http://dx.doi.org/10.2172/1365579.

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Akerib, D. S. LUX-ZEPLIN (LZ) Conceptual Design Report. Office of Scientific and Technical Information (OSTI), marzo 2015. http://dx.doi.org/10.2172/1251183.

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Penn, G. Staged energy cascades for the LUX FEL. Office of Scientific and Technical Information (OSTI), luglio 2004. http://dx.doi.org/10.2172/837421.

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ten Napel, Jan, Francesca Neijenhuis, Fleur Hoorweg e Martien Bokma-Bakker. Evaluatie voortgang PvA naar meer natuurlijke geboorten bij luxe vleesvee. Wageningen: Wageningen Livestock Research, 2019. http://dx.doi.org/10.18174/472867.

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Bhagavathula, Rajaram, Ronald Gibbons e Andrew Kassing. Roadway Lighting’s Effect on Pedestrian Safety at Intersection and Midblock Crosswalks. Illinois Center for Transportation, agosto 2021. http://dx.doi.org/10.36501/0197-9191/21-028.

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This study evaluates the visual performance of four intersection lighting designs and five midblock crosswalk lighting designs along with two pedestrian safety countermeasures (rectangular rapid flashing beacons and flashing signs) at three light levels. The study involved a pedestrian detection task, which was completed at night on a realistic roadway intersection and a midblock crosswalk. The results from the study showed that driver nighttime visual performance at intersection and midblock crosswalks was influenced by the lighting design and light level. Intersections should be illuminated to an average horizontal illuminance of 14 lux (1.3 fc). This light level ensures optimal visibility of pedestrians regardless of the lighting design (or luminaire layout) of the intersection. The average horizontal illuminance of 14 lux (1.3 fc) also increases the visibility of pedestrians when glare from oncoming vehicles is present. The 14 lux (1.3 fc) average horizontal illuminance is valid for all lighting designs evaluated except the lighting design that illuminated the exits of the intersection. When the exits of the intersection are illuminated, an average horizontal illuminance of 24 lux (2.2 fc) is needed to offset the disability glare from opposing vehicles. Midblock crosswalks should be illuminated to an average vertical illuminance of 10 lux (0.9 fc) to ensure optimal pedestrian visibility. Where overhead lighting is available, midblock crosswalk lighting designs that render the pedestrian in positive contrast are recommended. Where overhead lighting is not available, crosswalk illuminators can be used to illuminate midblock crosswalks. At night, pedestrian crossing treatments such as rectangular rapid flashing beacons and flashing signs should not be used for pedestrian visibility at midblock crosswalks. Pedestrians crossing treatments should be used in conjunction with overhead lighting or crosswalk illuminators at the established vertical illuminance to ensure optimal pedestrian visibility at midblock crosswalks.
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Burlage, R. S., Z. Yang, R. J. Palmer e Y. Khang. Development and application of the lux gene for environmental bioremediation. Office of Scientific and Technical Information (OSTI), settembre 1996. http://dx.doi.org/10.2172/378840.

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Wolfs, Frank. Final Report: Pushing the Dark-Matter Limit: Triggering LUX and LZ. Office of Scientific and Technical Information (OSTI), marzo 2017. http://dx.doi.org/10.2172/1481010.

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McMahon, Shane. CRADA Final Report: CRADA Number NFE-18-07342 with Lux Semiconductors, LLC. Office of Scientific and Technical Information (OSTI), settembre 2022. http://dx.doi.org/10.2172/1888908.

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Nadera, Made, e Rofi Uddarojat. Esensi Pengalaman Migras - 23 purna Tenaga Kerja Indonesia (TKI) menceritakan pengalaman di luar negeri yang membentuk keterampilan berwirausaha. Jakarta, Indonesia: Center for Indonesian Policy Studies, 2017. http://dx.doi.org/10.35497/270459.

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Wolfs, Frank, Eryk Druszkiewicz, Dev Ashish Khaitan, Wojtek Skulski, Yufan Qie, Jeanie Wolfs, Yue Wang e Christina Loniewski. Final Report DOE DE-SC0017891: "Pushing the Dark-Matter Limit: The LUX-Zeplin (LZ) Experiment.". Office of Scientific and Technical Information (OSTI), luglio 2019. http://dx.doi.org/10.2172/1545271.

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